rtc: ds1302 rtc support

This adds a basic ds1302 RTC driver, which is basically a cleanup and move
of the in-tree SH SecureEdge5410 code (which is currently located in
arch/sh/board/snapgear/rtc.c) to drivers/rtc.

This aims to be a building block that the M32R and CRIS code can be worked
on top of, so we can get rid of drivers/char/ds1302.c and
arch/cris/arch-v10/drivers/ds1302.c respectively, though more work is
needed for this.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 262 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-ds1302.c b/drivers/rtc/rtc-ds1302.c
new file mode 100644
index 000000000000..7b002ceeaa7d
--- /dev/null
+++ b/drivers/rtc/rtc-ds1302.c
@@ -0,0 +1,262 @@
+/*
+ * Dallas DS1302 RTC Support
+ *
+ *  Copyright (C) 2002  David McCullough
+ *  Copyright (C) 2003 - 2007  Paul Mundt
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License version 2.  See the file "COPYING" in the main directory of
+ * this archive for more details.
+ */
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/time.h>
+#include <linux/rtc.h>
+#include <linux/spinlock.h>
+#include <linux/io.h>
+#include <linux/bcd.h>
+#include <asm/rtc.h>
+
+#define DRV_NAME        "rtc-ds1302"
+#define DRV_VERSION     "0.1.0"
+
+#define RTC_CMD_READ    0x81            /* Read command */
+#define RTC_CMD_WRITE   0x80            /* Write command */
+
+#define RTC_ADDR_RAM0   0x20            /* Address of RAM0 */
+#define RTC_ADDR_TCR    0x08            /* Address of trickle charge register */
+#define RTC_ADDR_YEAR   0x06            /* Address of year register */
+#define RTC_ADDR_DAY    0x05            /* Address of day of week register */
+#define RTC_ADDR_MON    0x04            /* Address of month register */
+#define RTC_ADDR_DATE   0x03            /* Address of day of month register */
+#define RTC_ADDR_HOUR   0x02            /* Address of hour register */
+#define RTC_ADDR_MIN    0x01            /* Address of minute register */
+#define RTC_ADDR_SEC    0x00            /* Address of second register */
+
+#define RTC_RESET       0x1000
+#define RTC_IODATA      0x0800
+#define RTC_SCLK        0x0400
+
+#ifdef CONFIG_SH_SECUREEDGE5410
+#include <asm/snapgear.h>
+#define set_dp(x)       SECUREEDGE_WRITE_IOPORT(x, 0x1c00)
+#define get_dp()        SECUREEDGE_READ_IOPORT()
+#else
+#error "Add support for your platform"
+#endif
+
+struct ds1302_rtc {
+        struct rtc_device *rtc_dev;
+        spinlock_t lock;
+};
+
+static void ds1302_sendbits(unsigned int val)
+{
+        int i;
+
+        for (i = 8; (i); i--, val >>= 1) {
+                set_dp((get_dp() & ~RTC_IODATA) | ((val & 0x1) ?
+                        RTC_IODATA : 0));
+                set_dp(get_dp() | RTC_SCLK);    /* clock high */
+                set_dp(get_dp() & ~RTC_SCLK);   /* clock low */
+        }
+}
+
+static unsigned int ds1302_recvbits(void)
+{
+        unsigned int val;
+        int i;
+
+        for (i = 0, val = 0; (i < 8); i++) {
+                val |= (((get_dp() & RTC_IODATA) ? 1 : 0) << i);
+                set_dp(get_dp() | RTC_SCLK);    /* clock high */
+                set_dp(get_dp() & ~RTC_SCLK);   /* clock low */
+        }
+
+        return val;
+}
+
+static unsigned int ds1302_readbyte(unsigned int addr)
+{
+        unsigned int val;
+
+        set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
+
+        set_dp(get_dp() | RTC_RESET);
+        ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_READ);
+        val = ds1302_recvbits();
+        set_dp(get_dp() & ~RTC_RESET);
+
+        return val;
+}
+
+static void ds1302_writebyte(unsigned int addr, unsigned int val)
+{
+        set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
+        set_dp(get_dp() | RTC_RESET);
+        ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_WRITE);
+        ds1302_sendbits(val);
+        set_dp(get_dp() & ~RTC_RESET);
+}
+
+static int ds1302_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+        struct ds1302_rtc *rtc = dev_get_drvdata(dev);
+
+        spin_lock_irq(&rtc->lock);
+
+        tm->tm_sec      = BCD2BIN(ds1302_readbyte(RTC_ADDR_SEC));
+        tm->tm_min      = BCD2BIN(ds1302_readbyte(RTC_ADDR_MIN));
+        tm->tm_hour     = BCD2BIN(ds1302_readbyte(RTC_ADDR_HOUR));
+        tm->tm_wday     = BCD2BIN(ds1302_readbyte(RTC_ADDR_DAY));
+        tm->tm_mday     = BCD2BIN(ds1302_readbyte(RTC_ADDR_DATE));
+        tm->tm_mon      = BCD2BIN(ds1302_readbyte(RTC_ADDR_MON)) - 1;
+        tm->tm_year     = BCD2BIN(ds1302_readbyte(RTC_ADDR_YEAR));
+
+        if (tm->tm_year < 70)
+                tm->tm_year += 100;
+
+        spin_unlock_irq(&rtc->lock);
+
+        dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
+                "mday=%d, mon=%d, year=%d, wday=%d\n",
+                __FUNCTION__,
+                tm->tm_sec, tm->tm_min, tm->tm_hour,
+                tm->tm_mday, tm->tm_mon + 1, tm->tm_year, tm->tm_wday);
+
+        if (rtc_valid_tm(tm) < 0)
+                dev_err(dev, "invalid date\n");
+
+        return 0;
+}
+
+static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+        struct ds1302_rtc *rtc = dev_get_drvdata(dev);
+
+        spin_lock_irq(&rtc->lock);
+
+        /* Stop RTC */
+        ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) | 0x80);
+
+        ds1302_writebyte(RTC_ADDR_SEC, BIN2BCD(tm->tm_sec));
+        ds1302_writebyte(RTC_ADDR_MIN, BIN2BCD(tm->tm_min));
+        ds1302_writebyte(RTC_ADDR_HOUR, BIN2BCD(tm->tm_hour));
+        ds1302_writebyte(RTC_ADDR_DAY, BIN2BCD(tm->tm_wday));
+        ds1302_writebyte(RTC_ADDR_DATE, BIN2BCD(tm->tm_mday));
+        ds1302_writebyte(RTC_ADDR_MON, BIN2BCD(tm->tm_mon + 1));
+        ds1302_writebyte(RTC_ADDR_YEAR, BIN2BCD(tm->tm_year % 100));
+
+        /* Start RTC */
+        ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) & ~0x80);
+
+        spin_unlock_irq(&rtc->lock);
+
+        return 0;
+}
+
+static int ds1302_rtc_ioctl(struct device *dev, unsigned int cmd,
+                            unsigned long arg)
+{
+        switch (cmd) {
+#ifdef RTC_SET_CHARGE
+        case RTC_SET_CHARGE:
+        {
+                struct ds1302_rtc *rtc = dev_get_drvdata(dev);
+                int tcs_val;
+
+                if (copy_from_user(&tcs_val, (int __user *)arg, sizeof(int)))
+                        return -EFAULT;
+
+                spin_lock_irq(&rtc->lock);
+                ds1302_writebyte(RTC_ADDR_TCR, (0xa0 | tcs_val * 0xf));
+                spin_unlock_irq(&rtc->lock);
+                return 0;
+        }
+#endif
+        }
+
+        return -ENOIOCTLCMD;
+}
+
+static struct rtc_class_ops ds1302_rtc_ops = {
+        .read_time      = ds1302_rtc_read_time,
+        .set_time       = ds1302_rtc_set_time,
+        .ioctl          = ds1302_rtc_ioctl,
+};
+
+static int __devinit ds1302_rtc_probe(struct platform_device *pdev)
+{
+        struct ds1302_rtc *rtc;
+        int ret;
+
+        /* Reset */
+        set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
+
+        /* Write a magic value to the DS1302 RAM, and see if it sticks. */
+        ds1302_writebyte(RTC_ADDR_RAM0, 0x42);
+        if (ds1302_readbyte(RTC_ADDR_RAM0) != 0x42)
+                return -ENODEV;
+
+        rtc = kzalloc(sizeof(struct ds1302_rtc), GFP_KERNEL);
+        if (unlikely(!rtc))
+                return -ENOMEM;
+
+        spin_lock_init(&rtc->lock);
+        rtc->rtc_dev = rtc_device_register("ds1302", &pdev->dev,
+                                           &ds1302_rtc_ops, THIS_MODULE);
+        if (IS_ERR(rtc->rtc_dev)) {
+                ret = PTR_ERR(rtc->rtc_dev);
+                goto out;
+        }
+
+        platform_set_drvdata(pdev, rtc);
+
+        return 0;
+out:
+        kfree(rtc);
+        return ret;
+}
+
+static int __devexit ds1302_rtc_remove(struct platform_device *pdev)
+{
+        struct ds1302_rtc *rtc = platform_get_drvdata(pdev);
+
+        if (likely(rtc->rtc_dev))
+                rtc_device_unregister(rtc->rtc_dev);
+
+        platform_set_drvdata(pdev, NULL);
+
+        kfree(rtc);
+
+        return 0;
+}
+
+static struct platform_driver ds1302_platform_driver = {
+        .driver         = {
+                .name   = DRV_NAME,
+                .owner  = THIS_MODULE,
+        },
+        .probe          = ds1302_rtc_probe,
+        .remove         = __devexit_p(ds1302_rtc_remove),
+};
+
+static int __init ds1302_rtc_init(void)
+{
+        return platform_driver_register(&ds1302_platform_driver);
+}
+
+static void __exit ds1302_rtc_exit(void)
+{
+        platform_driver_unregister(&ds1302_platform_driver);
+}
+
+module_init(ds1302_rtc_init);
+module_exit(ds1302_rtc_exit);
+
+MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
+MODULE_VERSION(DRV_VERSION);
+MODULE_AUTHOR("Paul Mundt, David McCullough");
+MODULE_LICENSE("GPL v2");